DESCRIPTION (Investigator's Abstract): The focus of the research program is how neural circuits generate rhythmic behaviors and the mechanisms underlying neural and hormonal modulation of these networks. The principal investigator proposes to develop a new invertebrate model system, the Melibe buccal ganglion, which contains only 30, large neurons. The goal of the proposed research is to delineate the neural circuit of this ganglion in an effort to determine how it produces the patterned activity underlying swallowing behavior. Specific aims include: 1. Construction of a cellular map of the entire ganglion using both histological and electrophysiological techniques. 2. Characterization of the activity of each neuron in the ganglion using voltage sensitive dyes, a photodiode array detector and appropriate computer hardware and software. 3. Delineation of the synaptic connectivity of the network using traditional stimulation-recording techniques. 4. Development of a working model of the network, based on the results of the physiological and morphological studies. Preliminary data by the principal investigator has demonstrated that the buccal ganglion controls swallowing behavior and that the neurons of the buccal ganglion are accessible to standard intracellular recording, stimulating and staining intracellular recording, stimulating and staining techniques.